The present invention relates to a liquid crystal display device and a method of manufacturing the same, and in particular, to a liquid crystal display device and a method of manufacturing the same using a so-called in-plane switching method.
In a color liquid crystal display device employing the in-plane switching method, there are disposed two transparent substrates on both surface sides of a liquid crystal layer such that a display electrode and reference electrodes are arranged in a surface region corresponding to a pixel unit of the liquid crystal on either one of the transparent substrates. Light passing through the liquid crystal layer is modulated according to an electric field generated between the display electrode and the reference electrodes in parallel to the transparent substrate surfaces.
Provision of such color liquid crystal display substrates in the display device leads to an advantage that an image presented on the display can be clearly recognized by the viewer in a wide angle of visual field with respect to the display screen. Therefore, it has been well known that the display device using these substrates can be advantageously utilized to obtain a wide angle of visual field.
In a system in which the in-plane switching method is applied to a liquid crystal display device of a so-called active matrix configuration, a switching element is arranged in each of the pixel regions arranged in a matrix shape. When a scan signal is fed from a scan signal line, a switching element is activated in response thereto such that a video signal is supplied from a video signal line to the display electrode. In addition, a reference signal is supplied from a reference signal line to the reference electrodes.
The liquid crystal display device of this construction using the in-plane switching method has been described in detail, for example, in PCT WO91/10936 published Jul. 25, 1991 (Japanese Patent Publication Kohyo-5-505247) and JP-B-63-21907.
However, in the liquid crystal display device using the construction above, it is necessary to arrange the video signal lines to intersect the scan and reference signal lines. Furthermore, since the reference electrodes are disposed on both sides of the display electrode in each pixel domain, the device has a geometrically complex structure.
Therefore, in the manufacturing process of the liquid crystal display device, since there is unavoidably increased the chance of an electric short-circuit or linkage between the respective signal lines and/or between the signal lines and electrodes, which are to be inherently insulated from each other, a simple method of correcting the electric linkage has been desired.
Moreover, when compared with the conventional liquid crystal display device the liquid crystal display device using in-plane switching method additionally requires a reference signal line to supply a reference signal to the reference electrodes of each pixel. It has been reported that the probability of occurrence of an electric linkage is increased between the reference signal line and the video signal line intersecting each other with an insulation film arranged between the reference and video signal lines.
Additionally, since the reference signal line is fabricated as a common region to the pixels arranged in the y-axis direction, when an electric short-circuit occurs between a portion of the reference signal region and the video signal line, a display defect or failure takes place for all of the pertinent pixels. In consequence, there has been strongly desired a countermeasure of removing the disadvantage.